Photoreactive substrate analogues for prenyltransferase (farnesyl pyrophosphate synthetase) will be prepared. These analogues will be used to derivatize the catalytic site of this protein. The primary sequence of the enzyme will be determined and the portion of the protein involved in substrate binding and catalysis identified. The orientation of the substrates in the catalytic site will be determined by chemical shift and spin relaxation techniques. The phosphorous in the substrate, fluorine containing substrate analogues Mg2 ion and Mn2 ion will provide the labels necessary for these experiments.